Search

[Display omitted] In the present study, an innovative carbon self-doped g-C 3 N 4 (CCN) loaded with ultra-low CeO 2 (0.067–0.74 wt%) composite photocatalyst is successfully synthesized via a facile one-pot hydrothermal and calcination method. The CeO 2 /CCN exhibits superior photocatalytic performance for tetracycline degradation (78.9% within 60 min), H 2 O 2 production (151.92 μmol L-1 within 60 min), and Cr(VI) reduction (99.5% within 40 min), which much higher than that of g-C 3 N 4 , CCN, CeO 2 , and CeO 2 /g-C 3 N 4. The enhanced photocatalytic performance is originated from the fact that the doping of C can efficaciously broaden the utilization range of solar light and improve the reduction ability of photogenerated electrons. Meanwhile, the ultra-low loading of CeO 2 can effectually promote the migration of photogenerated electrons and enhance the specific surface area. Besides, the experiments of pH effect and cycle ability indicate that CeO 2 /CCN has excellent durability and stability. Finally, the photocatalytic mechanism of CeO 2 /CCN is systematically discussed. This work proves that combining element doping and semiconductor coupling is a promising strategy to design high-efficiency g-C 3 N 4 -based photocatalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • FePc/g-C 3 N 4 catalysts were successfully synthesized by a facile one-pot method. • π-π interaction between FePc and g-C 3 N 4 forms a fast electron transfer channel. • g-C 3 N 4 provides photogenerated electrons to accelerate Fe (III) / Fe (II) cycles. • CNFP exhibits excellent photo-Fenton performance for OTC degradation. • CNFP exhibits a wide pH range, good anti-interference ability and stability. Antibiotic contamination has become an environmental problem that cannot be ignored, and there is an endless demand for high performance advanced oxidation technologies to efficiently remove antibiotics from wastewater. Iron (II) phthalocyanine (FePc) with monoatomic dispersed iron sites has great potential for Fenton-like catalysis, but its tendency to aggregate in aqueous environments leads to self-degradation, poor electrical conductivity, and masking of active centers, which severely limits its practice application. Herein, aiming at these disadvantages, a novel FePc/g-C 3 N 4 (CNFP)/H 2 O 2 photo-Fenton system was constructed. In CNFP, the highly dispersed FePc on g-C 3 N 4 not only avoided the self-degradation caused by high aggregation, but also provided more active centers. Additionally, the π-π interaction between FePc and g-C 3 N 4 formed a quick-speed electron transfer routeway, which enabled the fast transfer of photogenerated electrons. g-C 3 N 4 as a photocatalytic center can continuously provide photogenerated electrons for FePc to realize the rapid regeneration of Fe(II). In CNFP/H 2 O 2 photo-Fenton system, the coexistence of radicals and non-radicals (OH, O 2 −, h+, and 1O 2) enhanced the anti-interference ability. The self-degradation analysis showed that FePc had obvious self-degradation in the photo-Fenton process, while CNFP had no self-degradation. Furthermore, the CNFP/H 2 O 2 photo-Fenton system was carefully evaluated by pH effect, ions effect, toxicity assessment, and cycling experiments, revealing its application potential in practical wastewater treatment. [ABSTRACT FROM AUTHOR]

• A novel benzene ring modified g-C 3 N 4 photocatalyst is successfully synthesized. • BCNNS exhibits excellent light response and the separation of charge carriers. • The modification of benzene ring can promote the activation of molecular oxygen. • BCCNS shows improved photocatalytic activity for OTC degradation. Popular graphitic carbon nitride (g-C 3 N 4) photocatalyst always faces the problems of weak visible light absorption and fast recombination of photogenerated electron-hole pairs. Herein, a novel benzene ring modified g-C 3 N 4 nanosheet (BCNNS) was synthesized by a simple calcination method. The degradation rate of oxytetracycline by BCNNS under visible light can reach 72% (within 60 min), significantly higher than that of the unmodified g-C 3 N 4 nanosheet (50%). And the degradation rate constant of BCNNS is 0.025 min−1, which is 2.1 times higher than that of g-C 3 N 4 (0.012 min−1). The improvement in the photocatalytic degradation performance can be attributed to the introduction of benzene ring, which can significantly broaden the light absorption range and intensify. In addition, the introduction of benzene ring can adjust the original electronic structure, thereby effectively suppressing the recombination of electron-hole pairs. Furthermore, density functional theory (DFT) calculations demonstrate that the introduction of benzene ring can significantly promote the surface adsorption of molecular oxygen and promote the transfer of electrons to molecular oxygen. This demonstrates that the embedded benzene ring can effectually advance the activation of molecular oxygen, which also well confirms that O 2 − and 1O 2 are the main active species in the system of BCNNS photocatalytic degradation of oxytetracycline. This study reveals that benzene ring modified g-C 3 N 4 has great potential in environmental purification, and provides a promising strategy for the removal of stubborn water contaminants. [ABSTRACT FROM AUTHOR]

The increasingly serious pollution of antibiotics brings an enormous threat to the ecological environment and human health. Graphite phase carbon nitride (g-C 3 N 4), as a popular photocatalytic material, is widely used in photocatalytic degradation of antibiotics in water. In order to make up for the shortage of g-C 3 N 4 monomer, CeO 2 /N-doped g-C 3 N 4 (CeNCN) composite photocatalysts co-modified with nitrogen doping and CeO 2 loading were designed and synthesized with the idea of expanding visible light absorption and promoting photogenerated carrier separation. CeNCN exhibits excellent photodegradation performance, the removal rate of tetracycline reached 80.09% within 60 min, which is much higher than that of g-C 3 N 4 (CN) and N-doped g-C 3 N 4 (NCN); and the quasi-first-order degradation rate constant is 0.0291, which is 7.86 and 2.29 times higher than CN and NCN. Electron spin resonance and free radical trapping experiments confirmed that h+, O 2 − and OH are the active substances in the photocatalytic system. After 5 cycles, the degradation efficiency of tetracycline still exceeds 75%, which indicates that CeNCN has good stability. This work proves that N-doping and CeO 2 loading can effectively broaden the photoresponse range of g-C 3 N 4 , facilitate the separation of photogenerated electron-hole pairs, and provide a reference for the construction of g–C 3 N 4 –based photocatalyst with high-efficiency photodegradation activity. [Display omitted] • CeO 2 /N-doped g-C 3 N 4 (CeNCN) photocatalyst was successfully first synthesized. • CeNCN exhibits excellent light response and the separation of charge carriers. • CeNCN exhibits significantly enhanced photocatalytic activity for TC degradation. • The proposed photocatalytic mechanism toward CeNCN photocatalyst is illustrated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Coordinative Fe-N x improved the catalytic ability of FeOCN for photo-Fenton process. • The consumption of H 2 O 2 was reduced in the photo-Fenton process over FeOCN. • FeOCN showed high catalytic performance for tetracycline degradation. • The improved charge separation favored Fe(III)/Fe(II) conversion. • FeOCN exhibited wide applicable pH range and anti-interference ability to anions. Tetracycline (TC) antibiotics have been widely used over the past decades, and their massive discharge led to serious water pollution. Photo-Fenton process has gained ever-increasing attention for its excellent oxidizing ability and friendly solar energy utilization ability in TC polluted water treatment. This work introduced coordinative Fe into oxygen-enriched graphite carbon nitride (OCN) to form FeOCN composites for efficient photo-Fenton process. Hemin was chosen as the source to provide the source of coordinative Fe-N x groups. The degradation efficiency of TC reached 82.1 % within 40 min of irradiation, and remained 76.9 % after five runs of reaction. The degradation intermediates of TC were detected and the possible degradation pathways were gained. It was found that h+, OH, and O 2 − played major roles in TC degradation. Notably, the photo-Fenton performance of FeOCN was stable in highly saline water or strong acid/base environment (pH 3.0–9.0). Besides, H 2 O 2 can be generated in-situ in this photo-Fenton process, which is favorable for practical application. It can be anticipated that the coordinative FeOCN composites will promote the application of photo-Fenton oxidation process in TC polluted water treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Porous bimetal-doped FTCN were successfully synthesized. • FTCN exhibited excellent photo-Fenton activity under visible light. • The important role played by bimetals in catalysts was investigated by DFT method. • The photo-Fenton mechanism of FTCN was discussed in deep. In this study, we synthesized Fe and Ti co-doped graphitic carbon nitride (FTCN) with high catalytic ability by a two-step calcination method. The photoelectrochemical results indicated that FTCN possessed a reduced bandgap and promoted photocarrier transfer efficiency, which enables FTCN excellent performance on oxytetracycline (OTC) degradation (90 % within 10 min). The main reactive oxygen species and the intermediates of OTC in the photo-Fenton process were obtained. Experimental data and density functional theory (DFT) were combined to explore the mechanism in depth. Interestingly, it was found that Fe and Ti respectively act as the main activation centers of H 2 O 2 and O 2 , while few oxygen-containing metal active sites participate in the activation process. The synergistic effect of bimetallic doping plays a significant role in enhancing the photo-Fenton catalytic performance. Hopefully, a new approach to design highly efficient multifunctional catalysts or dual single-atom catalysts can be developed. [ABSTRACT FROM AUTHOR]

• The characteristics of BP, h-BN, g-C 3 N 4 , graphene, and COFs are introduced. • The recent advances in element doping and heterojunction constructing are reviewed. • Organic amendment, hydroxyl modification, and dye sensitization are introduced. • The applications in HER, CO 2 RR, NRR, OER, and ORR are concluded. Semiconductor photocatalysis has been recognized as a feasible strategy for effective utilization of solar power to alleviate the energy shortage and environmental crisis. Efficient photocatalytic process over two dimensional (2D) ultrathin nanomaterial is one of the most paramount technologies for solving these problems. In this review, we begin with a brief introduction of five nonmetal-based 2D ultrathin nanomaterials (including black phosphorus (BP), hexagonal boron nitride (h-BN), covalent organic frameworks (COFs), graphene, and polymeric graphitic carbon nitride (g-C 3 N 4)), which mainly discusses the special characteristics of these materials. And then, as the main content of the article, recent advances of optimizing strategies for these five 2D materials are reviewed from the aspects of element doping and construction of heterojunction. We subsequently discuss the new strategies that may be effective for future optimization. Furthermore, the applications of nonmetal-based 2D photocatalysts in energy such as H 2 evolution, CO 2 reduction, N 2 fixation, O 2 evolution, and O 2 reduction are concluded. Finally, conclusions and outlooks are given for future potential directions. [ABSTRACT FROM AUTHOR]